Manufacture of hydrogen peroxide



July 8, 1958 P. J. FRlEL MANUFACTURE OF HYDROGEN PEROXIDE Filed Sept.12, 1956 INVENTOR. PATRICK J. FRIEL l I 5 5 Magnetic Flux (I0 gauss-OMFig. 2.

TORNEY tes l axtent ice -:MANUFACFE j 7 This invention relates to themanufacture of hydrogen peroxide, and moreparticularly to amethod forproducing hydrogen peroxide by the dissociation ofwater vapor in'a highvoltage dischargetube.

It has been known for some time that water vapor at ,lowpressures in theorder of 0.1 mm. to 1.0 mm. of

mercury absolute may be dissociated into hydrogen atoms and hydroxylradicals by the action of a high voltage discharge tube, and that thedissociation products may be condensed at'liquid air, temperatures toyield a product containing hydrogen peroxide. (See Discussions of theFaraday Society, No. 14, p. 104, 1953.) The maximum yield of'hydrogenperoxide, formed by the union of two hydroxyl radicals, is limited toabout 25 mol percent of the'water vapor charged since, due tothepresence of all of the hydrogen atoms at the condensing surface, thecompeting reactions H+H H and H+OH- H O will also take place.Furthermore, the hydrogen peroxide is obtained as a dilute solution inwater, a 57% by weight hydrogen peroxide solution being the strongestthat has heretofore been obtained. I

It is an object of this invention to provide a method whereby afterpassage of Water vapor through a high voltage discharge, the hydrogenatoms and hydroxyl radicals may be substantially separated from oneanother, so that, on condensation, the union of hydroxyl radicals willbe the chief reaction to give a high yield of a highly concentratedsolution of hydrogen peroxide.

1 Room .PERoxmE 1 Pat k; J- riel jfiwvmal i, Pa, a isn t0 D l(30mpagan-Philadelphia, Pm, acorporation ofNew'Jer-sey" q Applic Sep b 19 6, rial-N v6 s 6 partly incross-lsection, of an apparatus suitable forcarry- 7 toeifec't a displacementof H. atoms.

' As may be observed from Figure l ofthe drawing, the apparatusconsistsof ,areceptacle 1 in which the charge water is placed, a tube 2 oftapered cross-section for a,

' part of its length connected atits smallerendwithre- I find that theforegoing-object may be attained by I passing the dissociation productsfrom the high voltage I discharge through an inhomogenous magneticfield, prior to contact with a liquid air trap. Both the H atom and theOH radical are paramagnetiq'and will therefore be displaced in thedirection of the strongest part of the field. Since, due to inertia,displacement of the particles 'is inversely proportionate to their mass,the OH radical will be displaced only 4 the distance of the H atom.

The displacement of each particle is. .proportionalto the square-of thelength of its path in the field, and is also It has length and themagnetic flux, to effect a suflicient separation to enable the OHradicals to be passed through one conduit to the liquid air trap, wherethey condense on the surface and unite to form hydrogen peroxide, and topass the H atoms through a separate conduit to the atmosphere. Since themajority of the H atoms are thus removed from the reaction zoneion thesurface of in connection with .Figure 1 of the accompanying drawingwhich is a view,

ceptacle 1, and divided into conduits 3 and 4 at-its larger end.Conduit} connects directly withevacuat'ing means 5, while conduit-4 hasinterposed therein a liquid air trap 6.

In operation, receptacle. 1 is charged witha quantity of deaeratedwater, and evacuating means is started up' and operated to maintain theabsolutepressurejn tube '2 and conduits Sand-4 at a value of about 0.1mmt of mercury; Watervapor under the control of pressure j reducingvalve 1-a passes out of receptacle 1 into tube 2, which has an insidediameter of 5 cm. at its narrow end, and passes between electrodes 7 and8 where it is subjected to high voltage discharge, inorder to dissociateit into H atoms and OH radicals. move into the tapered section of tube2, where theyare subjected to a magnetic flux of 14,400 gauss/cm. in-

duced by magnet 9,-which has a length of 35 cm.v The taper of tube 2 issuch that its inside diameter at'the discharge end is 10 cm., whileconduit 3 has an inside diameter of 4 cm. and conduit 4 has an insidediameter of 4.5 cm. It may be calculated that the application of amagnetic flux of 14,400 gauss/cm. over' a path of 35 cm. will displacethe hydrogen atoms in the x direction a distance of about 5 cm., whiledisplacing the OH radi-v cals a distance ofonly 0.3 cm. This degree ofdisplacement will efiect an almost complete separation of H atoms fromOH radicals, the H atoms passing into conduit 3 to evacuating means 5,from which they are discharged through line 10. Substantially all the OHradi cals pass through conduit 4 and condense on the wall of liquid airtrap 6, which is maintained at liquid air temperature by boiling liquidair contained therein,make-up liquid air being added through line 11,while vapors are taken oiT through line 12. The OH radicals'condensed ontrap 6 'unite to form hydrogen peroxide, which builds up on the wall oftrap 6 as hydrogen peroxide ice. When the ice has built up to athickness such that the heat transfer through the ice and the Wall oftrap 6 is inadequate to maintainthe temperature of the surface of theice low enough to condense OH radicals (about C.) the processisinterrupted, liquid air is'removed from trap 6, and the trap isallowed to warm up to a temperature such that the hydrogen peroxidewill;

' re'-evacuated, and theprocess is placed back on stream While theforegoing description is directed to the manufacture of hydrogenperoxide using a specificsized apparatus with a magnetic field ofspecific length and flux strength, apparatus of diiferent size andstrengthof field may be constructed in accordance with the followingequation:

,, =(ia Xfi) a 2 2M dx 0;

where: d =deflection in the x direction =magnetic moment of the particle(,a'H) =ang1e between the field and the axis of the magnet r 2,842,490Patented July 8 1958,

These radicals then i 3 M :mass of the particle -=magnetic flux of thefield in the x direction l =length of the path in the field v =velocityof the particle in the z direction Thus, for a desired deflection of theH atoms of 5 cm., the magnetic flux required for various lengths of 1may be expressed as:

(for the calculation ,ucos(;tH)--l.7 Bohr magnetrons: l.576 l()-erg/gauss; v =the square of the z componenttof the most probablevelocity from the kinetic theory=1.66 l cm. /sec. M=mass of the H atom:1.66 10 Figure 2 of the accompanying drawing is a chart illustrating theflux required to effect a displacement of H atoms of 5 cm. at variousvalues of 1 other than that of the specific example. Similar charts maybe derived 4 from the above equations for other desired values of 11,.

I claim:

The method of manufacturing hydrogen peroxide which comprises passingwater vapor through a high voltage discharge at an absolute pressure notgreater than about 10 mm. of mercury, therein dissociating the watervapor to hydrogen atoms and hydroxyl radicals, passing the hydrogenatoms and hydroxyl radicals through a magnetic field of a length andstrength sufficient to effect separation of hydrogen atoms from hydroxylradicals by displacement of the hydrogen atoms in the direction of thestrongest part of the field, separately conducting the hydroxyl radicalsto contact with a surface maintained at a temperature not in excess ofl20 C., and recovering hydrogen peroxide formed by the union of hydroxylradicals on said surface.

References Cited in the file of this patent Discussion of the FaradaySociety, No. 14, pp. 104- (1953).

